Cells to Molecules: Structural EM at Newcastle University

光学显微镜所能提供的细胞细节水平有限，而且不可能用它们来观察细胞或分子内部特征的精细结构。透射电子显微镜（TEM）使用高能电子而不是光来产生图像，提供的细节是光学显微镜的1000多倍。利用透射电镜可以观察细胞内的结构，了解它们是如何形成的，甚至可以看到蛋白质和蛋白质机器内原子的排列。在过去的二十年里，TEM仪器背后的技术和用于从中获取图像的相机已经经历了重大的发展。用TEM成像的主要缺点之一是生物样品的对比度有限，以及由此产生的噪声对图像的影响。这使得我们的研究变得困难，因为我们很难清楚地看到我们正在观察的结构。现代tem配备了能够以非常低的噪点拍摄图像的相机，甚至可以捕捉电影，以观察到非常精细的细节，否则会丢失。一个主要的进步是在非常低的温度下制备样品，这使得细胞和分子可以在自然水合状态下观察，并最大限度地减少了显微镜中电子引起的样品损伤的扩散。这项技术被称为冷冻电镜，它允许细胞和蛋白质在一定程度上的细节成像，从而有可能看到蛋白质的单个氨基酸成分。我们的研究项目涵盖了广泛的主题，从了解肠道病原体艰难梭菌如何形成抗消毒剂孢子；到生产用于电子和导电聚合物材料的基于dna的纳米线。其他项目试图了解特定基因如何影响肾脏组织的形成。我们也对称为细胞周期蛋白依赖激酶的蛋白质如何与其伴侣蛋白相互作用以影响细胞分裂和编码蛋白质的RNA信息的产生感兴趣。这项工作对抗癌药物的开发具有启示意义。

Light microscopes are limited in terms of the level of detail they can provide of cells and it is not possible to use them to look at the fine structure of the internal features of cells or molecules. Transmission Electron Microscopes (TEM) use high energy electrons rather than light to produce images and provide over 1000 times the level of detail possible with a light microscope. Using a TEM it is possible to look at the structures within cells to see how they form and even see the arrangement of atoms within proteins and protein machines. In the last twenty years, the technology behind TEM instruments and the cameras used to acquire images from them have undergone significant developments. One of the major drawbacks of imaging with a TEM is the limited contrast available from biological samples and the resulting impact of noise on the images. This makes our studies difficult as it is often hard to see the structures we are looking at clearly. Modern TEMs are equipped with cameras capable of taking images with very low noise and even capturing movies to allow very fine detail to be observed that would otherwise be lost. One major advance has been the preparation of samples at very low-temperatures, this allows cells and molecules to be viewed in a naturally hydrated state and minimises the spread of sample damage caused by the electrons from the microscope. This technique is known as cryo-EM and permits cells and proteins to be imaged with a level of detail at which it is possible to see the individual amino-acid components of proteins.Our research projects cover a wide range of subjects from understanding how the intestinal pathogen Clostridium difficile forms disinfectant resistant spores; to the production of DNA-based nanowires for use in electronics and conductive polymer materials. Other projects seek to understand how particular genes influence the formation of kidney tissues. We are also interested in how proteins called cyclin dependent kinases interact with their partner proteins to influence cell division and the production of RNA messages encoding proteins. This work has implications for the development of anti-cancer drugs.